A conventional gas turbine engine is generally provided with one or more rotor assemblies with a disc and a circumferential array of blades. The rotor blades are disposed in corresponding retention slots of the disc with a radially extending gap between adjacent blades to accommodate thermal expansion. These rotor assemblies are used in the turbine section, the compressor section, or both. The blades are often provided with internal cooling channels, especially when used in the turbine section.
In some engine designs, the gaps between the blades can be substantial and conventional cover plates mounted on the rotor disc generally do not adequately seal this area. Cooling air can leak through these radial gaps and the blades, which produce an impeller effect due to their extremely high rotational speed, expel the cooling air radially through the gaps. This transverse cooling air leakage flow impedes and disturbs the gas path flow and can significantly reduce the gas turbine engine efficiency.
It is known to provide an annular ring located between the cover plate and the disc in effort to deflect the cooling air flow away from the gaps and redirect it into the gas path in the direction of the gas path flow. However, such a ring can be subject to unwanted movement or be misplaced during assembly or maintenance, thereby reducing its efficiency. Moreover, damage at one point of the ring necessitates the replacement of the entire ring.
Accordingly, there is a need for an improved rotor blade and method where air leakage through the gaps between adjacent blades is mitigated.